Published: Apr 12, 2010 2:11 PM EDT

"Exit Through the Gift Shop" guides you through the world of street art before showing you the door, leaving you — as all thought-provoking graffiti does — amused, thrilled, bewildered and a little confused about the nature of art.

The film is a curiosity. It's both an attempted documentary of an artistic movement and a bemused examination about why the movie failed in that mission. It was made by the renown British graffiti artist known as Bansky, whose creations appear secretly overnight on random walls the world over.

Bansky's works often suggest a wry comment on pop culture: a mural of Samuel L. Jackson and John Travolta from "Pulp Fiction" holding bananas rather than guns; a painting on the West Bank barrier of a girl pulled upward by balloons; British pound notes with Princess Diana's head replacing the Queen's.

Aside from apparently guiding the movie behind the camera, Banksy occasionally appears in front of it, too. Lounging leisurely in a chair, he's hooded and shrouded in shadow, his voice altered.

He introduces the film, apologizing that it's "not 'Gone With the Wind,'" but that he thinks there may be "a moral in there somewhere."

The central figure of the movie isn't Bansky, but an enthusiastic, mutton-chopped Frenchman named Thierry Guetta. A celebrity-obsessed Los Angeles family man ("C'est Shaq," he exclaims), Guetta obsessively videotapes his life.

When Guetta comes in contact with street artists like Invader and Shepard Fairey, he quickly ingratiates himself to them and becomes the artists' de facto documentarian.

"The man who would film anything had stumbled into an underground world," intones the film's narrator, the Welsh actor Rhys Ifans.

Guetta knows little about art or even filmmaking, but he's game. He excitedly follows these artists (whose works now can fetch tens of thousands of dollars at auction) as they, like burglars, scramble across rooftops at night.

As time goes by, Guetta amasses a great library of footage. Much of it is riveting — a rare window into people who spend a lot of energy keeping their identities secret and obscuring their methods.

When fame finds Bansky and the other graffiti artists, they urge Guetta to assemble his documentary. He responds with a 90-minute movie, "Life Remote Control," a plotless, almost demented mess.

Realizing that they had entrusted the wrong person — "someone with mental problems with a camera," says Bansky — Bansky decides to take the reins, and "Exit Through the Gift Shop" is the result.

There's a twist, though. While Bansky is sifting through the wreckage, he suggests Guetta try creating street art, himself — thereby unwittingly creating a monster.

In Los Angeles, Guetta remakes himself as "Mister Brainwash" and — with the help of a large staff and notices from Bansky and Fairey — fixes up an extravagant hit debut show. The lavish attention he gets and the prices paid for his derivative, manufactured paintings, astonishes Bansky and the rest.

They are left shaking their heads at this counterfeit "overnight artist." Looking for a lesson, Bansky shrugs, "Maybe it means art is a bit of a joke."

It's a deflating, albeit sensible conclusion, especially when it comes at the heels of a movie that celebrates art's inventiveness. It's also fitting: One of Bansky's most famous pranks was stealthily hanging his own works in the Louvre.

"Exit Through the Gift Shop" begins with a beautiful montage of street artists at work, set to Richard Hawley's "Tonight the Streets Are Ours." As fascinating a story as Guetta's is, one can't help but wish street art could have gotten the documentary it deserved.

"Exit Through the Gift Shop," a Producers Distribution Agency release, is rated R for some language. Running time: 87 minutes. Three stars out of four.

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Motion Picture Association of America rating definitions:

G — General audiences. All ages admitted.

PG — Parental guidance suggested. Some material may not be suitable for children.

PG-13 — Special parental guidance strongly suggested for children under 13. Some material may be inappropriate for young children.

R — Restricted. Under 17 requires accompanying parent or adult guardian.

NC-17 — No one under 17 admitted.